1. Field of the Invention
This invention generally relates to a rapid prototyping method and a fabricating apparatus using such a method. More specifically, it relates to a rapid prototyping method of slicing an image of a product to be fabricated into a number of layers, preparing a mold sheet for each of the slices of the product with a cavity adapted to the profile of the corresponding slice, feeding the cavity of the mold sheet with a powdery material, pressurizing the material, repeating the above steps to form a multilayer structure for a complete product and sintering the structure to produce a finished product. It also relates to a fabricating apparatus using such a method.
2. Background Art
A number of rapid prototyping (RP) methods of slicing an image of a newly designed product, actually preparing slices of the product and producing a product of the product by assembling the slices have recently been finding commercial applications. Such methods may largely be classified into three types. Photosetting resin is used for a method of the first type, with which an image of a newly developed product is sliced and slices of the product are sequentially formed from photosetting resin by irradiating the resin with laser for setting before they are assembled to produce a mock-up. A method of the second type slices an image of a product and mold sheets are prepared for the respective slices and laid one on the other to form a multilayer structure for a product. Finally, with a method of the third type, a thin layer of a powdery material is formed on a table and subjected to a process involving heating, melting and solidifying by means of laser before the layer is pressurized to produce a slice of the product. The steps are repeated and thereby integrated slices of the product are formed to produce a multilayer structure and any unnecessary powdery material is removed from it before it is sintered to produce a complete product. A rapid prototyping method proposed by the applicant of the present patent application (Japanese Patent Application No. 8-238768) belongs to the third type.
While the above described rapid prototyping methods are effective for molding, they are accompanied by certain respective drawbacks. Methods of the first and second types are not adapted to directly produce a metal product. If a metal product is to be produced by any of such methods, it requires the use of a time-consuming conventional process of preparing a female mold for casting on the basis of a mock up produced by a method of the first or second type. If a multilayer structure is formed from resin, there can be produced various by-products that eventually contaminate the environment. While methods of the third type are advantageous in that they can even produce a nearly net shaped metal product if it is solely made of a powdery material, they have a major disadvantage of not being adapted to prepare high precision objects.
In view of the above identified problems of known methods of the art, it is therefore the object of the present invention to provide a rapid prototyping method using sintering that can directly and hence economically mold a high density and high precision product of any profile within a short period of time from any desired powdery material or a combination of different powdery materials. In addition, the other advantages of a method according to the invention are that it is friendly to the environment and that an economical advantage may be enjoyed.